In-memory pub-sub system

This is an implementation of an in-memory pub-sub system (for ex Kafka). There is a publisher interface and a subscriber interface. The pub-sub system is thread safe and operates on a "pull" model from the customer's perspective.

Building and running the code

The programming language used is Java8 (as a gradle project).

Unzip the contents and from the project's root directory (called rootDir), run ./gradlew clean build fatJar --refresh-dependencies : This will build the jar and place it under rootDir/build/libs

For running the code, from the rootDir run java -jar build/libs/<filename>.jar

The input orders.json file is under src/main/resources directory. If this file changes, please build the jar once again before running as the CSVs are loaded from the classpath.

Testing the code

There are tests for all major flows using groovy and spock testing framework.

Run ./gradlew test from the rootDir.

Notes

Design patterns used: Singleton, callback, pubsub.